Limitations associated with linear-array probes in photoacoustic tomography are partially compensated by using advanced beamformers that exploit the temporal and spatial coherence of the recorded signals, such as Delay Multiply and Sum (DMAS), Minimum Variance (MV) or coherence factor (CF), among others. However, their associated signal processing leads to an overestimation of the spatial resolution, as well as alterations in the reconstructed object size. Numerical and experimental results reported here support this hypothesis. First, we show that the Rayleigh criterion (RC) is the most suitable choice to characterize the spatial resolution instead of the Point Spread Function (PSF) when considering advanced beamformers. Then, we observe that several advanced beamformers fail to properly reconstruct target sizes slightly above the spatial resolution, underestimating their size. This work sheds light on the suitability of this type of beamformers combined with linear probes for determining sizes and morphology in photoacoustic images.

中文翻译：

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在基于线性阵列的 PAT 系统中使用先进波束形成器的空间分辨率和重建尺寸精度

光声断层扫描中与线性阵列探头相关的局限性可以通过使用先进的波束形成器来部分补偿，这些波束形成器利用记录信号的时间和空间相干性，例如延迟乘法和求和 (DMAS)、最小方差 (MV) 或相干因子 (CF)等。然而，它们相关的信号处理导致空间分辨率的高估，以及重建对象尺寸的改变。这里报告的数值和实验结果支持这一假设。首先，我们表明，在考虑高级波束形成器时，瑞利准则（RC）是表征空间分辨率的最合适选择，而不是点扩散函数（PSF）。然后，我们观察到几种先进的波束形成器无法正确重建略高于空间分辨率的目标尺寸，从而低估了它们的尺寸。这项工作揭示了这种类型的波束形成器与线性探头相结合用于确定光声图像中的尺寸和形态的适用性。